Power Management in a Mobile Device

ABSTRACT

Apparatuses, systems and methods for reducing power consumption during standby operation of a mobile device are disclosed. A page decoding algorithm can be stored in nonvolatile memory during standby. The page decoding algorithm can be executed from the nonvolatile memory, when the mobile device is awakened from a sleep state to determine if there is any activity such as an incoming call. No power is required for the nonvolatile memory to maintain storage of the algorithm so that the power requirement during standby of the mobile device is reduced.

FIELD OF DISCLOSURE

Embodiments of the invention are related to improving battery life. Moreparticularly, embodiments of the invention are related to improvingmobile device battery life by a structure which reduces the averagecurrent used during standby operation. In one embodiment, the structurewithin the mobile device may incorporate a Magnetoresistive RandomAccess Memory (MRAM) to store program data during standby.

BACKGROUND

With the vast and increasing numbers of functions to be performed bymobile devices comes an increased emphasis on battery life. In additionto increasing the ability of a battery to produce and maintain asustainable long life, there is also an increasing interest into theability of a mobile device to reduce requirements for total currentconsumption, not only during actual operation of the mobile device butalso during quiescent states. A mobile device should be able to react toa call, a message, or other incoming communication in rapid order. Thisquick reaction ability conventionally involves the mobile device topreserve the processor state and the contents of high speed randomaccess memory during the “sleep” phase of a mobile device, henceutilizing a “sleep current”.

An example of the current utilization of a conventional mobile deviceduring a quiescent state is shown in FIG. 1. When the mobile device isin the standby state, it may be in a sleep phase 110 for multiples ofsome period. For example, in a CDMA system the sleep phase may be formultiples of 1.28 seconds. Each paging channel monitoring phase lastsapproximately 30 ms. As seen in the FIG. 1, even during the sleep phase110 there may be an approximately 11 mA current draw, and during awakeup phase 120 (e.g., during the Quick Page Channel (QPCH) decode)there may be a current draw of approximately 86 mA. As a result theaverage total current required from the battery during the sleep phase110 and QPCH decode is approximately 2 mA([(2.56−0.30)×1/2.56]+(0.30×86)/2.56=2 mA). As can be seen, for theillustrated typical operation, approximately one half of the totalcurrent utilization during standby is due to the sleep current of 1 mA.This current may typically be used in conventional architectures inorder to preserve the state of volatile memory/internal registers.

FIG. 2 represents a conventional mobile device memory partitioningscheme wherein the power may be controlled by a Power ManagementIntegrated Circuit (PMIC) 10. Power can be supplied to the mobile deviceprocessor (MDP) 12, the Flash memory 16 and the Synchronous DynamicRandom Access Memory (SDRAM) 14 during the “active” operation of themobile device, such as, for example, calling and responding to anincoming call. The MDP 12 may include logic for mobile device operationand analog interfaces, and can further include one or moremicroprocessors and/or Digital Signal Processors (DSPs). The SDRAM 14unit may be a volatile memory. The MDP 12 and the SDRAM may use theaforementioned 1 mA power during the sleep phase to preserve theirstate.

SDRAM such as shown in FIG. 2 is a subset of Random Access Memories(RAMs) in general. RAM can be stand alone devices and/or can beintegrated or embedded within devices that use the RAM, such asmicroprocessors, microcontrollers, application specific integratedcircuits (ASICs), system-on-chip (SoC), and other like devices. RAM canbe volatile or non-volatile. Volatile RAM loses its stored informationwhenever power is removed. Non-volatile Flash memory can maintain itsmemory contents even when power is removed from the memory. AlthoughFlash memory has advantages in the ability to maintain its contentswithout having power applied, it may have slower read/write times thanvolatile RAM. Moreover, there may be limitations regarding the number ofwrite operations which can be performed on a Flash memory.

Accordingly, given the aforementioned conventional memory technologies,system designers may contend with difficult compromises between mobiledevice performance and energy efficiency, even during the sleep phase ofthe mobile device.

SUMMARY

Exemplary embodiments of the invention are directed to systems,apparatus and methods for improving operational battery life by reducingcurrent demand during “sleep” periods by using low power high speed nonvolatile memory for storing program code.

Accordingly an embodiment of the invention can include a mobile devicecomprising: a nonvolatile memory configured to store a paging channelalgorithm; a processor configured to execute the paging channelalgorithm out of the nonvolatile memory and configured to decode apaging channel in response to a timing signal; and a controllerconfigured to output the timing signal to the processor.

Another embodiment of the invention can include a power managementapparatus comprising: a controller for controlling power to a mobiledevice during a standby phase which includes a sleep phase and a wakeupphase, said controller including a timer to initiate a power-up signalat an end of the sleep phase and a power-down signal during the sleepphase; a nonvolatile memory device configured to store a page algorithmto initiate an operation of the mobile device during the standby phase;and a processor configured to execute the page algorithm out of thenonvolatile memory in response to the power-up signal from saidcontroller.

Another embodiment of the invention can include a method of powermanagement in a mobile device, comprising: storing program code relatedto a page algorithm in a nonvolatile memory, wherein the program code isexecuted during a wakeup phase; powering down the mobile device whilemaintaining power to a timer; determining an interval for the wakeupphase by the timer; powering up the mobile device during the wakeupphase; and executing the program code out of the nonvolatile memory.

Another embodiment of the invention can include a mobile device powermanagement system comprising: means for storing program code related toa page algorithm in a nonvolatile memory, wherein the program code isexecuted during a wakeup phase; means for powering down the mobiledevice while maintaining power to a timer; means for determining aninterval for the wakeup phase by the timer; means for powering up themobile device during the wakeup phase; and means for executing theprogram code out of the nonvolatile memory.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofembodiments of the invention and are provided solely for illustration ofthe embodiments and not limitation thereof.

FIG. 1 illustrates a graph of a conventional current time profile of amobile device during its quiescent phase.

FIG. 2 illustrates a block diagram of a conventional mobile device powerpartitioning scheme.

FIG. 3 illustrates a block diagram of a system for a mobile device powerpartitioning arrangement.

FIG. 4 is a flow chart illustrating a process for managing power of amobile device.

DETAILED DESCRIPTION

Aspects of the invention are disclosed in the following description andrelated drawings directed to specific embodiments of the invention.Alternate embodiments may be devised without departing from the scope ofthe invention. Additionally, well-known elements of the invention willnot be described in detail or will be omitted so as not to obscure therelevant details of the invention.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. Likewise, the term “embodiments ofthe invention” does not require that all embodiments of the inventioninclude the discussed feature, advantage or mode of operation.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of embodiments ofthe invention. As used herein, the singular forms “a”, “an” and “the”are intended to include the plural forms as well, unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises”, “comprising,”, “includes” and/or “including”, whenused herein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Further, many embodiments are described in terms of sequences of actionsto be performed by, for example, elements of a computing device. It willbe recognized that various actions described herein can be performed byspecific circuits (e.g., application specific integrated circuits(ASICs)), by program instructions being executed by one or moreprocessors, or by a combination of both. Additionally, these sequence ofactions described herein can be considered to be embodied entirelywithin any form of computer readable storage medium having storedtherein a corresponding set of computer instructions that upon executionwould cause an associated processor to perform the functionalitydescribed herein. Thus, the various aspects of the invention may beembodied in a number of different forms, all of which have beencontemplated to be within the scope of the claimed subject matter. Inaddition, for each of the embodiments described herein, thecorresponding form of any such embodiments may be described herein as,for example, “logic configured to” perform the described action.

As used herein, the term “mobile device” may refer to any type ofwireless communication device which may transfer information over anetwork. The mobile device may be any cellular mobile terminal, personalcommunication system (PCS) device, personal navigation device, laptop,personal digital assistant, or any other suitable capable of receivingand processing network and/or Satellite Position System signals.Moreover, as used herein, the term “network” may refer to any wirelesscommunication network, including a wireless wide area network (WWAN), awireless local area network (WLAN), a wireless personal area network(WPAN), and so on. A WWAN may be a Code Division Multiple Access (CDMA)network, a Time Division Multiple Access (TDMA) network, a FrequencyDivision Multiple Access (FDMA) network, an Orthogonal FrequencyDivision Multiple Access (OFDMA) network, a Single-Carrier FrequencyDivision Multiple Access (SC-FDMA) network, and so on. A CDMA networkmay implement one or more Radio Access Technologies (RATs) such ascdma2000, Wideband-CDMA (W-CDMA), and so on. Cdma2000 includes IS-95,IS-2000, and IS-856 standards. A TDMA network may implement GlobalSystem for Mobile Communications (GSM), Digital Advanced Mobile PhoneSystem (D-AMPS), or some other RAT. GSM and W-CDMA are described indocuments from a consortium named “3rd Generation Partnership Project”(3GPP). Cdma2000 is described in documents from a consortium named “3rdGeneration Partnership Project 2” (3GPP2). 3GPP and 3GPP2 documents arepublicly available. A WLAN may be an IEEE 802.11x network, and a WPANmay be a Bluetooth network, an IEEE 802.15x, or some other type ofnetwork. The techniques may also be used for any combination of WWAN,WLAN and/or WPAN.

FIG. 3 illustrates a block diagram of a mobile device processor andpower management system 20 having an exemplary power partitioningarrangement. Other well known elements and features of the mobile devicesuch as the user interface, antenna, battery, transceivers, memorymanagers, etc. will not be illustrated or described herein. Likewise,well known processes/algorithms performed by the mobile device, such asreceiving and decoding pages, sleep cycles, paging cycles, memorymanagement, etc. will not be discussed in detail herein. However, itwill be appreciated these well known elements and processes are includedin mobile devices in embodiments of the invention.

In order to reduce power requirements during quiescent/standbyoperation, the system 20 may store selected program code inMagnetoresistive Random Access Memory (MRAM) 26 without consuming powerduring the sleep phase of the mobile device. During the sleep phase, thecurrent consumption of system 20 may be primarily attributed to poweringa timer (not shown) which may integrated into the PMIC 22, a separatedevice or may be integrated into any element in the mobile device thatwill be at least partially powered for the timer. For convenience andconsistency of explanation the timer will be considered to be integratedinto the PMIC 22 in the following descriptions. However, it will beappreciated that embodiments of the invention are not limited to thediscussed timer arrangement and the timer functionality may reside inspecific circuits, by program instructions being executed by one or moreprocessors, or by a combination of both.

The timer can be used to determine when quick page decoding occurs.Magnetoresistive Random Access Memory (MRAM) 26 may provide non-volatilestorage for data and/or program instructions. The program instructionsmay include, for example, the algorithms for monitoring the pagingchannel. In various embodiments, program instructions responsible forperforming different functions may also be stored. The mobile device mayspend the majority of its time in the quiescent state. The mobile devicemay only become active (i.e., “wake up”) when the user initiates a call,or when the status of the paging channel indicates that a response isappropriate. Upon entering the active state, the mobile device maytransfer the application program code appropriate for providing aresponse from MRAM 26 to Flash memory 29 and/or SDRAM 28. However,usually it will be the case that no response will be required, and themobile device can power down until it is time to decode the next pagingchannel.

System 20 includes the mobile device processor (MDP) 24, which maytransfer data and/or program code to/from Flash memory 29 and/or MRAM 26across memory interface EBI2. The MDP 24 may also transfer data and/orprogram code with SDRAM 28 across memory interface EBI1. Although shownas separate from the MDP 24, the MRAM 26, Flash memory 29, and/or theSDRAM 28 could reside on the digital portion of the die within the MDP24. Such packaging arrangements could eliminate any size impact on thesystem 20 while reducing power consumption. Accordingly it will beappreciated that the configurations illustrated and discussed herein aremerely provided for convenience of explanation and embodiments of theinvention are not limited to the these examples. For example, thefunctional blocks and the associated functionalities illustrated inrelation FIG. 3 may be separated in various manners or may be integratedinto one functional device.

The PMIC 22 may control and supply power to each of the components insystem 20 over dedicated power lines (indicated in bold). This controlcan be used to determine the sleep/awake phases of the mobile device inorder to save power. As mentioned above, the PMIC may further include atimer (not shown) which can be used to determine the appropriate time toperform a quick decode of the paging channel. During the wakeup phase,the PMIC 22 may supply power to each of the components of system 20shown in FIG. 3. During the sleep phase, the PMIC 22 may only providepower to its internal timer so the paging channel can be properlydecoded. The PMIC may include a processor and/or other configurablelogic (e.g., FPGA) so it may be programmed to configure the system 20for the various operational modes.

As described previously, for a conventional mobile device there may bean average current draw of, for example, 2 mA for quiescent operation.In these conventional devices, fifty percent of this current (1 mA) maybe used to preserve the state of volatile memory. The system of FIG. 3may reduce the sleep current by having the MDP copy a paging channeldecode algorithm to the MRAM 26. MRAM 26 is able to retain the algorithmin a ready condition without drawing current because MRAM 26 is a lowpower, non-volatile memory. Because MRAM has the additional capabilityof high speed operation, program code stored therein may be directlyread out of the MRAM 26 for execution by the MDP 24. Therefore becausethe algorithm for monitoring the paging channel can be executed out ofMRAM 26, the MDP 24 and the SDRAM 28 can then be powered down when notmonitoring the paging channel, i.e. during the 2.56 s sleep phases.While the other device are powered down during the sleep phase, thetimer resident in the PMIC 22 is operated in order to power up, themobile device in time to monitor the paging channel. Due to thenon-volatile nature of MRAM 26, the program code stored in MRAM 26 maynot be lost or corrupted during the power shut down.

In one embodiment, a mobile device may utilize the memory architecturesand power partitioning described herein. The current draw during the“sleep” interval for the mobile device may be reduced to approximately10 μA during intervals between Quick Page Channel (QPCH) decodes. Withthe reduction of the conventional 1 mA “sleep” current, the averagecurrent requirement during quiescent operation is reduced by 50 percent.

FIG. 3 shows an embodiment of the power partitioning system wherenon-volatile storage may be partitioned between MRAM 26 and Flash memory29. Because the cost of providing significant amounts of non-volatilestorage using MRAM may be prohibitive, in some embodiments portions ofprogram code and/or data, which will be read and directly executed bythe MDP as it exits from the sleep state, will be stored in MRAM 26.Other code not requiring quick access may be stored in Flash memory.However, as MRAM technology matures and costs are reduced, otherembodiments may replace the Flash memory and/or SDRAM, and only use MRAMfor all of the program code and/or data storage.

The various memory modules can be stand alone devices or can beintegrated or embedded within devices that use the memory, such asmicroprocessors, microcontrollers, application specific integratedcircuits (ASICs), system-on-chip (SoC), and other like devices as willbe appreciated by those skilled in the art. Random Access Memory (RAM)can be volatile or non-volatile. Volatile RAM loses its storedinformation whenever power is removed. Non-volatile RAM can maintain itsmemory contents even when power is removed from the memory. Althoughnon-volatile RAM has advantages in the ability to maintain its contentswithout having power applied, conventional non-volatile RAM,conventionally taking the form of Flash memory, may have slowerread/write times than volatile RAM. Flash memory may also havelimitations on the number of times it can be written to before it startsto malfunction. Magnetoresistive Random Access Memory (MRAM) is anon-volatile memory technology that has response (read/write) timescomparable to volatile memory. In contrast to conventional RAMtechnologies which store data as electric charges or current flows, MRAMuses magnetic elements. The nonvolatile memory of MRAM 26 provides fastaccess time comparable to the access time of SRAM. Additionally, MRAM 26also provides for a substantially greater number of write operationsbefore failure, when compared with the limited number of writeoperations available for Flash memory. Thus the MRAM memory partitioningscheme of FIG. 3 provides approximately twice the standby life for abattery operated mobile device, because it reduces the current usage inhalf for standby/quiescent operation.

FIG. 4 illustrates a flowchart of the operation of the partitioningscheme which may be performed in system 20. The mobile device mayacquire a paging channel and timing information (Block 51) (e.g., atboot up). The information may be read out of Flash memory 29, orobtained using other conventional approaches. Subsequently, program codewhich may be executed after the MDP 24 exits from the sleep phase may becopied from the Flash memory 29 to the MRAM 26 (Block 52). As mentionedpreviously, this program code may include the paging channel decodealgorithm. Other embodiments may include program code for otherfunctionality (e.g., code for operating the user interface such as thekeyboard and/or display). The PMIC 22 may then be programmed to wake upthe mobile device at predetermined times to perform paging channeldecoding (Block 53). After being programmed, the PMIC 22 may power downthe components in the mobile device except for the timer within the PMIC(Block 54). The timer may then control whether it is time to decode thepaging channel (Block 55). After each expiration of the timing period,the PMIC 22 directs the MDP 24 to power up and execute out of MRAM 26the stored program code which decodes the paging channel (Block 56).

If the message decoded from the paging channel indicates there is anincoming communication (Block 57), program code (which providesinstruction for the MDP 24 to execute the appropriate functionality tohandle the incoming communication) may be copied from Flash memory 29 toSDRAM 28. Once the incoming communication terminates (Block 59), theprocess may return to Block 53 where the PMIC is programmed to wake upthe mobile device for the next paging channel decode.

If the message decoded from the paging channel indicates there is noincoming communication, program control is transferred back to Block 53,where the process in Blocks 53-57 may continue to repeat until anotherincoming call is detected

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The methods, sequences and/or algorithms described in connection withthe embodiments disclosed herein may be embodied directly in hardware,in a software module executed by a processor, or in a combination of thetwo. A software module may reside in RAM memory, flash memory, ROMmemory, EPROM memory, EEPROM memory, registers, hard disk, a removabledisk, a CD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor.

Accordingly, an embodiment of the invention can include a computerreadable media embodying a method for reducing power consumption duringstandby operation of a mobile device. Accordingly, the invention is notlimited to illustrated examples and any means for performing thefunctionality described herein are included in embodiments of theinvention.

While the foregoing disclosure shows illustrative embodiments of theinvention, it should be noted that various changes and modificationscould be made herein without departing from the scope of embodiments ofthe invention as defined by the appended claims. For example, othernonvolatile memory devices (e.g., Spin Transfer Torque MRAM (STT-MRAM)),which are able to store the paging algorithm without power beingrequired to retain the algorithm could be used instead of the MRAMdiscussed herein. Likewise, the functions, steps and/or actions of themethods in accordance with the embodiments of the invention describedherein need not be performed in any particular order. Furthermore,although elements of the invention may be described or claimed in thesingular, the plural is contemplated unless limitation to the singularis explicitly stated.

1. A mobile device comprising: a nonvolatile memory configured to storea paging algorithm; a processor configured to execute the pagingalgorithm out of the nonvolatile memory and configured to decode apaging channel in response to a timing signal; and a controllerconfigured to output the timing signal to the processor.
 2. The mobiledevice of claim 1, wherein the nonvolatile memory is MagnetoresistiveRandom Access Memory (MRAM).
 3. The mobile device of claim 1, wherein aprocessor is a mobile device processor (MDP).
 4. The mobile device ofclaim 3, wherein said MRAM is integrated into the mobile deviceprocessor MDP.
 5. The mobile device of claim 1, wherein the controlleris configured to supply power to an operational part of the mobiledevice during a paging channel monitoring phase and is configured toremove power from the operational part of the mobile device duringintervals between the paging channel monitoring phase.
 6. The mobiledevice of claim 5, further comprising: a Flash memory device; and aSynchronous Dynamic Random Access Memory (SDRAM), wherein the SDRAMcommunicates with the MDP on a first memory interface and wherein theFlash memory communicates with the MDP and the nonvolatile memory on asecond memory interface.
 7. The mobile device of claim 6, wherein theoperational part of the mobile device includes the MDP, Flash memorydevice, SDRAM and nonvolatile memory.
 8. The mobile device of claim 1,wherein the controller comprises a timer configured to generate thetiming signal.
 9. The mobile device of claim 1, wherein the nonvolatilememory is Spin Transfer Torque MRAM (STT-MRAM).
 10. A power managementapparatus comprising: a controller for controlling power to a mobiledevice during a standby phase which includes a sleep phase and a wakeupphase, said controller including a timer to initiate a power-up signalat an end of the sleep phase and a power-down signal during the sleepphase; a nonvolatile memory device configured to store a pagingalgorithm to initiate an operation of the mobile device during thestandby phase; and a processor configured to execute the pagingalgorithm out of the nonvolatile memory in response to the power-upsignal from said controller.
 11. The power management apparatus of claim10, wherein the nonvolatile memory device is at least one ofMagnetoresistive Random Access Memory (MRAM) or Spin Transfer TorqueMRAM (STT-MRAM).
 12. The power management apparatus of claim 10, whereinthe paging algorithm includes code to monitor and decode a pagingchannel.
 13. A method of power management in a mobile device comprising:storing program code related to a page algorithm in a nonvolatilememory, wherein the program code is executed during a wakeup phase;powering down the mobile device while maintaining power to a timer;determining an interval for the wakeup phase by the timer; powering upthe mobile device during the wakeup phase; and executing the programcode out of the nonvolatile memory.
 14. The method of power managementof claim 13, wherein said nonvolatile memory is at least one ofMagnetoresistive Random Access Memory (MRAM) or Spin Transfer TorqueMRAM (STT-MRAM).
 15. The method of power management of claim 13, whereinexecuting the program code comprises decoding a paging channel
 16. Themethod of power management of claim 15, further comprising: detecting anincoming communication directed to the mobile device.
 17. The method ofpower management of claim 16, further comprising: copying code from aFlash memory to a Synchronous Dynamic Random Access Memory (SDRAM); andresponding to the incoming communication.
 18. The method of powermanagement of claim 13, further comprising: acquiring paging channel andtiming information.
 19. A mobile device power management systemcomprising: means for storing program code related to a page algorithmin a nonvolatile memory, wherein the program code is executed during awakeup phase; means for powering down the mobile device whilemaintaining power to a timer; means for determining an interval for thewakeup phase by the timer; means for powering up the mobile deviceduring the wakeup phase; and means for executing the program code out ofthe nonvolatile memory.
 20. The mobile device power management systemaccording to claim 19, wherein said storing program code is at least oneof Magnetoresistive Random Access Memory (MRAM) or Spin Transfer TorqueMRAM (STT-MRAM).